Fuel injection valve

Abstract

A valve element is movable in a main body for opening and closing the nozzle hole. A pressure control chamber is formed at an end of the valve element and configured to receive high-pressure fuel to bias the valve element so as to close a nozzle hole. A first communication passage communicates the pressure control chamber with a low pressure side. An accommodating chamber is located downstream of the first communication passage and acommodates a valve member. A low-pressure opening is for exhausting fuel from the accommodating chamber. The valve member has a valve portion to control fuel flowing from the pressure control chamber to the low pressure side. The accommodating chamber and the low-pressure opening therebetween has a passage, which defines a throttle portion.

1 . A fuel injection valve for injecting fuel into a combustion chamber of an internal combustion engine, the fuel injection valve comprising:
 a valve element;   a main part having a nozzle hole and accommodating the valve element, which is movable for opening and closing the nozzle hole, the main part further having a pressure control chamber, which is formed at an end of the valve element on an opposite side of the nozzle hole and configured to receive fuel at high pressure to bias the valve element in a valve-closing direction to close the nozzle hole, a first communication passage, which is for communicating the pressure control chamber with a low-pressure side, an accommodating chamber, which is located downstream of the first communication passage, and a low-pressure opening, which is for discharging the fuel from the accommodating chamber to an outside of the main part;   a valve member accommodated in the accommodating chamber and having an end provided with a valve portion for opening and closing the first communication passage to control discharge of the high-pressure fuel from the pressure control chamber to the low-pressure side; and   a solenoid configured to generate an electromagnetic force for actuating the valve member,   wherein the accommodating chamber and the low-pressure opening therebetween has a passage, which therein defines a throttle portion.   
   
   
       2 . The fuel injection valve according to  claim 1 ,
 wherein the main part has one end defining the nozzle hole,   the main part has an other end provided with the solenoid,   the solenoid includes a coil and a stator,   the stator supports the coil and configured to attract the valve member,   the stator has a low-pressure passage, which has one end communicated with the accommodating chamber, and an other end communicated with low-pressure opening, and   the low-pressure passage has the throttle portion.   
   
   
       3 . The fuel injection valve according to  claim 1 ,
 wherein the valve body is located between the solenoid and the first communication passage and configured to support the valve member so as to be movable in opening and closing directions,   the valve body defines the accommodating chamber,   the valve body has a second communication passage for communicating the accommodating chamber with the low-pressure opening, and   the second communication passage has the throttle portion.   
   
   
       4 . The fuel injection valve according to  claim 1 ,
 wherein the valve member includes the valve portion and a main portion,   the main portion supports the valve portion,   the valve body is located between the solenoid and the first communication passage and configured to support the main portion so as to be movable in opening and closing directions,   the valve body defines the accommodating chamber,   the main portion has a third communication passage for communicating the accommodating chamber with the low-pressure opening, and   the third communication passage has the throttle portion.   
   
   
       5 . The fuel injection valve according to  claim 1 ,
 wherein the main part has a first leak passage for leading fuel from a slide clearance between the valve element and the main part to the low-pressure opening,   the main part has a second leak passage for communicating the accommodating chamber with the first leak passage, and   the second leak passage has the throttle portion.   
   
   
       6 . The fuel injection valve according to  claim 1 , further comprising:
 a first biasing unit configured to exert first biasing force to bias the valve member in the valve-closing direction; and   a second biasing unit configured to exert second biasing force to bias the valve portion in the valve-opening direction,   wherein the second biasing force of second biasing unit is smaller than the first biasing force of the first biasing unit.   
   
   
       7 . The fuel injection valve according to  claim 1 , wherein the throttle portion is configured to restrict reduction in pressure in the accommodating chamber when the valve portion opens the first communication passage to communicate the pressure control chamber with the low-pressure side. 
   
   
       8 . The fuel injection valve according to  claim 1 , wherein the throttle portion is an orifice, which reduces a cross sectional area in the passage between the accommodating chamber and the low-pressure opening. 
   
   
       9 . The fuel injection valve according to  claim 8 , wherein the orifice is integrally formed with the passage between the accommodating chamber and the low-pressure opening. 
   
   
       10 . The fuel injection valve according to  claim 1 ,
 wherein the valve member includes the valve portion and a disc portion,   the disc portion is formed from a magnetic material and substantially in a disc-shape, and   the disc portion is configured to be attracted from the solenoid.   
   
   
       11 . The fuel injection valve according to  claim 1 , wherein the first communication passage has an orifice configured to restrict pressure in the pressure control chamber from exerted to the accommodating chamber when the valve portion opens the first communication passage.